The present invention relates generally to underwater electrical and/or fiber-optic cable systems, such as underwater telecommunication systems, and is particularly concerned with an apparatus and method for providing branching and re-distribution of circuits in such a system after installation.
Currently, it is very difficult to re-connect or re-distribute circuits when an electrical/optical cable system has been previously installed underwater, such as on the ocean floor. The present technology involves grappling and retrieval of cables from the ocean floor, such that they often have to be drawn up from several miles of ocean depth, and subsequently separated and re-terminated via splicing on board a cable laying ship, using ship-board facilities. This procedure is extremely laborious, time-consuming and expensive. Also, such procedures are very vulnerable to weather and ocean conditions, since storms or other inclement weather conditions can severely limit or jeopardize the successful completion of such operations.
It is an object of the present invention to provide a new and improved cable branching apparatus and method for an underwater electrical/optical cable system.
According to one aspect of the present invention, an underwater cable branching apparatus is provided, which comprises an elongate cable junction housing for positioning in line between two cables for installation underwater, the housing having a first junction at one end having a through bore for receiving the end of a first underwater cable and a second junction at the opposite end having a through bore for receiving the end of a second underwater cable, a pair of connectors in the housing for releasably connecting the end of the first cable to the end of the second cable, a connector mounting mechanism in the housing including a first pivotal linkage for moveably mounting the first connector for movement between a first position aligned with the second connector for connecting the first and second cable ends together in line, and a second position rotated upwardly and out of the housing for allowing the first cable end to be connected to another cable, and a second pivotal linkage for moveably mounting the second connector for movement between an extended, first position aligned with the first connector for connecting the first and second cable ends in line, and a second position rotated upwardly and out of the housing for connection of the second cable end to another cable, the housing having an upper opening for allowing rotation of said connectors out of the housing for re-connection to additional cables.
The housing may be provided with a door or doors for normally closing the upper opening, which can be opened by a remote oceanic vehicle or ROV when the connectors are to be separated and moved out of the housing. The connectors may be wet mateable underwater optical or electro-optical connectors which are designed for sealed, releasable underwater connection of electrical and/or optical fiber circuits in underwater cables. Suitable wet mateable connectors are described, for example, in U.S. Pat. Nos. 5,738,535 or 6,017,227 of Cairns, U.S. Pat. No. 6,315,461 of Cairns, or pending U.S. patent application Ser. No. 09/761,917 of Cairns et al. filed Jan. 17, 2001, the contents of each of which is incorporated herein by reference.
In an exemplary embodiment of the invention, a spherical or ball joint device is provided at each end of the housing for providing ready articulation of the cable entry. This provides a wide range of flexibility at the joint. The pivotal linkages may be associated with handles for gripping by an ROV in order to move the connectors in order to release the connection and move each connector into position for connection to another cable end connector.
The cable branching apparatus of this invention therefore permits multiple cable junction housings to be positioned over the length of a planned cable system, at any points where the joining of one or more branch cables may later be desired, months or even years after the initial installation. Later, at any location where branching is required, a separate junction box unit can be deposited on the sea floor adjacent the cable junction housing, the connector ends in the housing can be separated, and the junction box can be cable connected to the respective cable ends. All of these operations can be readily carried out at the ocean floor by a remotely operated underwater vehicle or ROV.
According to another aspect of the present invention, a cable branching system is provided which comprises at least one elongate connector housing for releasably connecting the ends of two underwater cables together, first and second cables extending into opposite ends of the housing and having end connectors releasably connected together inside the housing, a junction box having a first set of ports and a second set of ports, and an internal routing assembly for connected any selected port of the first set to a selected port of the second set, and third and fourth cables for selectively connecting a first port of the first set to the end connector of the first cable and a second port of the first set to the end connector of the second cable when the first and second cable ends are released.
The cable connector ends compries underwater mateable connectors, as described above, as do the junction box ports. Such connectors are capable of being mated or unmated while entirely submerged in sea water, while keeping the circuits completely sealed and protected from the surrounding water. These connectors retain their sealing capability even when submerged to oceanic depths of miles below sea level. The use of the cable junction apparatus and method of this invention greatly enhances the speed and efficiency with which sub-sea cable systems can be deposited, expanded and/or re-circuited.
According to another aspect of the present invention, a method of releasably joining cable ends and subsequently separating the cable ends and joining them into new circuits is provided, which comprises the steps of:
securing an end connector of a first underwater cable to a first pivotal linkage assembly inside a housing having an opening, the pivotal linkage assembly being movable to move the end connector between a lowered position in the housing and a raised position extending out of the housing;
securing an end connector of a second underwater cable to a second pivotal linkage assembly inside the housing, the second pivotal linkage assembly being movable to move the end connector between a lowered position in the housing, and a raised position extending out of the housing;
releasably securing the two end connectors together with the first and second pivotal linkage assemblies in the lowered position;
at a later date, disconnecting the end connectors and moving the second pivotal linkage assembly into a lowered, retracted position;
moving the first and second pivotal linkage assemblies into the raised position; and
securing the end connectors of third and fourth underwater cables to the respective end connectors of the first and second cables.
The method and apparatus of this invention allows installation of branching devices along each line when laying a new, sub-oceanic cable network for telecommunications or the like. Subsequent branching and recircuiting can then be readily performed by an ROV on the ocean floor at any desired branching apparatus location. Further revisions can be made at a later date, whenever required, substantially increasing the flexibility and modification capabilities of such systems. The performance of modifications and additions on the ocean floor by an ROV will significantly reduce the hazards to both equipment and personnel, by avoiding the need to raise a previously laid cable through possibly miles of ocean depth onto a cable laying ship, and then separate and re-splice the cable on board the ship. Branching and re-circuiting operations, as well as initial installation, will be less vulnerable to adverse weather conditions which can otherwise cause substantial, and expensive, delays in such operations.